Multi-beam lidar systems and methods for detection using the same

ABSTRACT

The present disclosure provides a multi-beam LiDAR system. The multi-beam LiDAR system includes a transmitter having an array of laser emitters. Each laser emitter is configured to emit a laser beam. The multi-beam LiDAR system also includes a receiver having an array of photodetectors. Each photodetector is configured to receive at least one return beam that is reflected by an object from one of the laser beams. The laser emitter array includes a plurality of laser emitter boards perpendicular to a horizontal plane. Each laser emitter board has a plurality of laser emitters. The plurality of laser emitters in the laser emitter array are staggered along a vertical direction. The photodetector array includes a plurality of columns of photodetectors. One of the laser emitter boards corresponds to one column of photodetectors.

CROSS REFERENCE TO RELATED APPLICATION

This application is continuation of U.S. patent application Ser. No.16/726,035, filed on Dec. 23, 2019, which is a continuation ofInternational Application No. PCT/CN2019/106273, filed on Sep. 17, 2019,entitled “MULTI-BEAM LIDAR SYSTEMS AND METHODS FOR DETECTION USING THESAME,” which claims priority to Chinese Patent Application No.201811085374.2, filed on Sep. 18, 2018, and Chinese Patent ApplicationNo. 201811086579.2, filed on Sep. 18, 2018, the entire contents of eachof which are incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to optical signal detection devices, suchas a light detection and ranging (LiDAR) device, and more particularlyto LiDAR systems using multi-beam laser emitters for detecting objectsin the surrounding environment.

BACKGROUND

Optical sensing systems, such as LiDAR systems, have been widely used inautonomous driving. LiDAR systems are used to detect the position,speed, and even contours of an object in the environment and also toproduce high-definition maps. For example, a typical LiDAR systemmeasures a distance to a target by illuminating the target with pulsedlaser beams and receiving the reflected pulses with a sensor, such as aphotodetector. Differences in the wavelengths, phases, and/or returntime of the laser beams can then be used to calculate the distance andto make digital three-dimensional (3D) representations of the target.Because using a laser beam as the incident light can map physicalfeatures with high resolution, a LiDAR system is particularly suitablefor applications such as sensing in autonomous driving and/orhigh-definition map surveys.

A LiDAR system normally includes a transmitter that emits pulsed laserbeams. The transmitter further has one or more laser emitters. Withinthe same length or area of the transmitter, the more laser emitters areprovided, the more laser beams the LiDAR system emits for scanning, andthus the higher resolution the LiDAR system achieves. As a result, theresolution of the LiDAR system typically depends on the density of thelaser emitters provided along a direction or within an area of thetransmitter.

Existing multi-beam LiDAR systems, which can emit multiple laser beamssimultaneously, includes multiple laser emitters. In order to achievehigher resolution of detection, the conventional wisdom is to mount asmany laser emitters as possible. Therefore, the transmitter circuits ofthe system have grown highly complicated along with the increasing sizethereof. Other problems which traditional LiDAR systems suffer frominclude sophisticated internal structure, high overall weight, and shortlife cycles.

Embodiments of the present disclosure address the above problems byproviding LiDAR systems using multi-beam laser emitters for detectingobjects in the surrounding environment, as well as methods using thesame.

SUMMARY

Embodiments of the disclosure provide a multi-beam LiDAR system. Themulti-beam LiDAR system includes a transmitter having an array of laseremitters. Each laser emitter is configured to emit a laser beam. Themulti-beam LiDAR system also includes a receiver having an array ofphotodetectors. Each photodetector is configured to receive at least onereturn beam that is reflected by an object from one of the laser beams.The laser emitter array includes a plurality of laser emitter boardsperpendicular to a horizontal plane. Each laser emitter board has aplurality of laser emitters. The plurality of laser emitters in thelaser emitter array are staggered along a vertical direction. Thephotodetector array includes a plurality of columns of photodetectors.One of the plurality of the laser emitter boards corresponds to one ofthe plurality of columns of photodetectors.

Embodiments of the disclosure also provide a method for detection by amulti-beam LiDAR system. The method includes emitting laser beams by atransmitter. The transmitter has an array of laser emitters. The methodalso includes receiving return beams by a receiver that are reflected byan object from the laser beams. The receiver has an array ofphotodetectors. The laser emitter array includes a plurality of laseremitter boards perpendicular to a horizontal plane. Each laser emitterboard has a plurality of laser emitters. The plurality of laser emittersin the laser emitter array are staggered along a vertical direction. Thephotodetector array includes a plurality of columns of photodetectors.One of the plurality of laser emitter boards corresponds to one of theplurality of columns of photodetectors.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of an exemplary vehicle equippedwith a LiDAR system, according to embodiments of the disclosure.

FIG. 2 illustrates a block diagram of an exemplary LiDAR device having atransmitter and a receiver, according to embodiments of the disclosure.

FIG. 3 illustrates a top view of an exemplary multi-beam LiDAR system,according to embodiments of the disclosure.

FIG. 4A illustrates a schematic diagram of an exemplary emitter laserarray of the multi-beam LiDAR system, according to embodiments of thedisclosure.

FIG. 4B illustrates a schematic diagram of an exemplary arrangement oflaser emitter boards of the multi-beam LiDAR system, according toembodiments of the disclosure.

FIG. 4C illustrates a schematic diagram of an exemplary photodetectorarray of the multi-beam LiDAR system, according to embodiments of thedisclosure.

FIG. 5 illustrates a top view of another exemplary multi-beam LiDARsystem, according to embodiments of the disclosure.

FIG. 6 illustrates a top view of yet another exemplary multi-beam LiDARsystem, according to embodiments of the disclosure.

FIG. 7 illustrates an explosive view of an exemplary multi-beam LiDARsystem, according to embodiments of the disclosure.

FIG. 8 illustrates a schematic diagram of an exemplary multi-beam LiDARsystem, according to embodiments of the disclosure

FIG. 9 illustrates an explosive view of an exemplary multi-beam LiDARsystem, according to embodiments of the disclosure

FIG. 10 illustrates a flow chart of an exemplary method for detectionusing the multi-beam LiDAR system, according to embodiments of thedisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary embodiments,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

An optical signal detection system, such as a LiDAR system, may usemultiple emitters, such as laser emitters, to emit laser beams fordetecting objects within the environment surrounding the LiDAR system.For example, laser emitters can emit laser light generated throughoptical amplification based on simulated emission of electromagneticradiation, which in turn may correspond to electrical signals, such ascurrent or voltage signals, from another part of the LiDAR system. Thelaser light may be controlled to emit, often in the form of laser beams,at certain intervals and towards certain directions. Also, the opticalsignal detection system may use one or more photodetectors to detectoptical signals (e.g., laser light) reflected by objects. For example, aphotodetector can convert optical signals to electrical signals, such ascurrent or voltage signals. The electrical signals may be amplified byan amplifier, such as a transimpedance amplifier (TIA), for subsequentprocessing. When the LiDAR system detects the surrounding environment,high density of the vertically emitted laser beams enables the LiDARsystem to achieve high scanning resolution. One way to achieve highdensity of laser beams is to align a large number of laser emittersalong one direction within a certain length unit on an emitter board ofa transmitter of the LiDAR system. In a typical LiDAR transmitter, allemitters may be disposed on a single emitter board. Because of thephysical limitation of the single emitter board, such as the limitationof the fabrication technique, vertical density for emitters on a singleemitter board approaches its upper limit.

Embodiments of the present disclosure provide an improved optical signaldetection system, such as a multi-beam LiDAR system, having a laseremitter array and a photodetector array. The term “array” as used hereinmeans a group of elements forming a complete unit. The array is notlimited to an orderly arrangement of such elements (e.g., laser emittersor photodetectors). The elements may be arranged in any manner as longas the same or similar purpose and result of the current disclosure areachieved. For example, the laser emitter array may have a plurality oflaser emitters staggered along a vertical direction, and each laseremitter board may have a plurality of laser emitters. The photodetectorarray may have a plurality of columns of photodetectors, one of theplurality of columns of photodetectors may correspond to one of theplurality of laser emitter boards. Because laser emitters may bedisposed on different emitter boards in a staggered fashion along thevertical direction, the density of emitters along the vertical directioncan be significantly increased. Accordingly, the resolution and otherrelated performance of the optical signal detection system may beimproved.

FIG. 1 illustrates a schematic diagram of an exemplary vehicle 100equipped with a multi-beam LiDAR optical signal detection system 102 (ormulti-beam LiDAR system 102 for simplicity), according to embodiments ofthe disclosure. Consistent with some embodiments, vehicle 100 may be anautonomous driving vehicle or a survey vehicle configured for acquiringdata for constructing a high-definition map, 3D buildings, terrestrialfeatures, or city modeling.

As illustrated in FIG. 1, vehicle 100 may be equipped with multi-beamLiDAR system 102 mounted to a body 104 via a mounting structure 108.Mounting structure 108 may be an electro-mechanical device installed orotherwise attached to body 104 of vehicle 100. In some embodiments ofthe present disclosure, mounting structure 108 may use screws,adhesives, or other suitable mounting mechanisms. Vehicle 100 may beadditionally equipped with a sensor 103 inside or outside body 104 usingany suitable mounting mechanisms. Sensor 103 may include sensors used ina navigation unit, such as a Global Positioning System (GPS) receiverand one or more Inertial Measurement Unit (IMU) sensors. It iscontemplated that the manner in which multi-beam LiDAR system 102 orsensor 103 can be mounted on or equipped with vehicle 100 is not limitedto the example shown in FIG. 1. It may be modified depending on thetypes of multi-beam LiDAR system 102, sensor 103, and/or vehicle 100, sothat the desirable sensing performance under the present disclosure maybe achieved.

Consistent with some embodiments, multi-beam LiDAR system 102 and sensor103 may be configured to capture data as vehicle 100 moves along atrajectory. For example, a transmitter of multi-beam LiDAR system 102 isconfigured to scan the surrounding and acquire point clouds. Multi-beamLiDAR system 102 may include one or more LiDAR devices configured tomeasure distance to a target by illuminating the target with pulsedlaser beams and measuring the reflected pulses with a receiver. Thelaser beams used by multi-beam LiDAR system 102 may be ultraviolet,visible, or near infrared. As vehicle 100 moves along the trajectory,LiDAR system 102 may continuously capture data. Each set of datacaptured at a certain time range is known as a data frame. Multiple dataframes may be subsequently combined, with the assistance of sensor data,to construct high-definition maps.

FIG. 2 illustrates a block diagram of an exemplary LiDAR optical signaldetection device 200 (or LiDAR device 200 for simplicity), such as thatused in multi-beam LiDAR system 102. Multi-beam LiDAR device 200 mayinclude a transmitter 202 and a receiver 204. Transmitter 202 may emitlaser beams within a scan angle as it moves (e.g., rotates, swings,etc.). The scan angle can be a horizontal angle, a vertical angle, or acombination of both. Transmitter 202 may include a laser source (notshown) that further includes multiple laser emitters. Each laser emittermay emit a laser beam. Thus, transmitter 202 may emit multiple laserbeams 207. The multiple laser emitters may form an array of laseremitters.

In some embodiments, multi-beam LiDAR device 200 may optionally includea rotating reflection mirror (not shown). Rotating reflection mirror maybe implemented by a tilting mirror, a prism, a group of mirrors, etc.Rotating reflection mirror may be provided as a component independentfrom, and disposed outside transmitter 202 and receiver 204. It may bedriven by a rotary component that changes the direction of laser beamsemitted from transmitter 202, thus creating a wider scan angle. Itsrotation may further cause return beams reflected by an object in thesurrounding environment to be received by receiver 204. Thus, rotatingreflection mirror may replace the function of a rotating apparatus(discussed below) while not affecting the function and result of themulti-beam LiDAR device 200 according to the present disclosure. Inembodiments where rotating reflection mirror is not equipped, multi-beamLiDAR device 200 can still achieve the same 360-degree rotation with theassistance of the rotating apparatus.

In some embodiments, transmitter 202 can emit multiple laser beamssimultaneously within its scan angle as it moves (e.g., rotates, swings,etc.). In other embodiments, transmitter 202 can emit multiple laserbeams sequentially, such as a stream of pulsed laser beams in differentdirections within its scan angle as it moves, as illustrated in FIG. 2.

Consistent with the embodiments of the present disclosure, the lasersource may generate laser beams in the ultraviolet, visible, or nearinfrared wavelength range. In some embodiments, each laser emitter ofthe laser source may be a pulsed laser diode (PLD), a vertical-cavitysurface-emitting laser (VCSEL), a fiber laser, etc. For example, a PLDmay be a semiconductor device similar to a light-emitting diode (LED) inwhich the laser beam is created at the diode's junction. In someembodiments, a PLD includes a PIN diode in which the active region is inthe intrinsic (I) region, and the carriers (electrons and holes) arepumped into the active region from the N and P regions, respectively.Depending on the semiconductor materials, the wavelength of incidentlaser beams 207 provided by a PLD may be smaller than 1,800 nm, such as405 nm, between 445 nm and 465 nm, between 510 nm and 525 nm, 532 nm,635 nm, between 650 nm and 660 nm, 670 nm, 760 nm, 785 nm, 808 nm, 848nm, 905 nm, or 1550 nm. It is understood that any suitable laser emittermay be used as an emitter in the laser emitter array for emitting laserbeams 207.

In some embodiments, when leaving multi-beam LiDAR device 200, one ofthe multiple laser beams 207, laser beam 209, may be projected to anobject 212 in a first direction. Object 212 that reflects laser beam 209may include a wide range of objects, including, for example, metallicobjects, non-metallic objects, vehicles, bicycles, pedestrians,billboards, road signs, cement pavements, rocks, rain, chemicalcompounds, aerosols, clouds, and even single molecules. Multi-beam LiDARdevice 200 may further include a transmitter optical unit 208, which maybe used to collimate laser beams 207 and/or to focus laser beams foremission to the surrounding environment.

In some embodiments, receiver 204 may be configured to detect a returnbeam 211 that is reflected by object 212 from laser beam 209. Receiver204 can collect return beams reflected by object 212 and outputelectrical signals indicating the intensity of the return beams.Although only one laser beam is shown in FIG. 2, a person of ordinaryskill in the art would understand that two or more laser beams may beemitted from multi-beam LiDAR device 202, reflected by object 212, andreceived by receiver 204 as return beams.

As illustrated in FIG. 2, multi-beam LiDAR device 200 may include areceiver optical unit 214 and a receiver 204. Receiver optical unit 214may be configured to collect light from all directions within its fieldof view (FOV). As an example, return beam 211 may be collected byreceiver optical unit 214. Return beam 211 may be reflected by object212 and have the same wavelength as laser beam 209.

Receiver 204 may include a photodetector array (not shown), which mayfurther include a plurality of photodetectors and may be configured todetect return beam 211 reflected from object 212. In some embodiments,each of the photodetectors in the photodetector array may convert alaser light (e.g., return beam 211) collected by receiver optical unit214 into an electrical signal 218 (e.g., a current or a voltage signal).Electrical signal 218 may be generated when photons are absorbed in aphotodiode. In some embodiments of the present disclosure, thephotodetectors of the photodetector array may include a PIN detector, aPIN detector array, an avalanche photodiode (APD) detector, a APDdetector array, a single photon avalanche diode (SPAD) detector, a SPADdetector array, a silicon photomultiplier (SiPM/MPCC) detector, aSiP/MPCC detector array, or the like.

In some embodiments, multi-beam LiDAR device 200 may include a signalprocessor 220 configured to process electrical signal 218. For example,signal processor 220 may include an analog to digital converter toconvert electrical signal 218 that may be an analog signal to a digitalsignal. In another example, signal processor 220 may include one or morefilters, noise reducers, signal enhancer, or the like to improve thesignal-to-noise ratio (SNR) of electrical signal 218. Signal processor220 may include a microprocessor, a digital signal processor (DSP), amicrocontroller, a field programmable gate array (FPGA), and/or othersuitable devices or chips capable of processing electrical signal 218.

FIG. 3 illustrates a top view of an exemplary multi-beam LiDAR system300, according to embodiments of the disclosure. Multi-beam LiDAR system300 may be one implementation of, thus having the same composition anddesign as, multi-beam LiDAR system 200 in FIG. 2. In some embodiments,multi-beam LiDAR system 300 may include a laser emitter array 110 and aphotodetector array 120.

In some embodiments, laser emitter array 110 may include two or morelaser emitter boards. In the example illustrated in FIG. 3, five laseremitter boards 111, 112, 113, 114, and 115 (hereinafter “laser emitterboards 111-115”) are arranged on a horizontal plane (e.g., the planedefined by x-axis and z-axis, or simply “x-z plane”), and each laseremitter board may extend along a vertical direction (e.g., along y-axis,as shown in FIG. 4A), which is perpendicular to the horizontal plane. Insome embodiments, the horizontal plane may be a plane parallel to thesea level. In other embodiments, the horizontal plane may be a planeparallel to a surface on which the vehicle mounted with multi-beam LiDARsystem 300 is travelling. Each laser emitter board may include aplurality of laser emitters aligned in a vertical direction.

FIG. 4A illustrates a schematic diagram of an exemplary laser emitterarray of multi-beam LiDAR system 300, according to embodiments of thedisclosure. As illustrated in FIG. 4A, laser emitter array 110 mayinclude a plurality of laser emitter boards 111-115 perpendicular to ahorizontal plane. Each of laser emitter boards 111-115 may include aplurality of laser emitters staggered along the vertical direction. Forexample, when being projected horizontally along the x-axis onto avirtual vertical surface 119, the laser emitters on laser emitter boards111-115 are staggered vertically on the virtual surface 119. The term“staggered” used herein means that the laser emitters on adjacent laseremitter boards have a position shift along a direction. In this example,laser emitters from adjacent laser emitter boards are not of the samevertical height along the vertically direction (e.g., y-axis direction).As a result, the laser beams emitted by the plurality of laser emittersdo not coincide with each another, and the projection path of each laseremitter does not overlap with each other either. Thus, the number oflaser beams per unit length along the vertical direction is increased,and therefore the density of emitted laser beams along that direction isalso improved. In this way, because the laser emitters in laser emitterarray 110 are staggered along a vertical direction, multi-beam LiDARsystem 300 may emit laser beams of higher vertical density, thusincreasing its vertical resolution and other related performances.

It is also contemplated that, in some embodiments, laser emitters inemitter array 110 may not be staggered vertically on the horizontalplane (e.g., x-z plane). For example, when multi-beam LiDAR system 300rotates about an axis that lies within the x-z plane, laser emitters inemitter array 110 may be staggered along a horizontal direction (thatis, along an axis in the x-z plane), parallel to the rotation axis ofmulti-beam LiDAR system 300. Accordingly, the photodetector array on thereceiving side of the multi-beam LiDAR system may also needcorresponding change in its configuration. A person of ordinary skill inthe art, learning the staggered arrangement of laser emitters taught inthe present disclosure, would know how to apply the teaching of thepresent disclosure to other implementations of a multi-beam LiDAR systemas well.

In some embodiments, at least one of the plurality of laser emitterboards may be at an angle with another laser emitter board. When thelaser emitter boards are perpendicular to a horizontal plane (e.g., thex-z plane), the angle represents the angle viewed from the verticaldirection (e.g., along the y-axis). When the angle is not 0 or 180degrees, the two laser emitter boards are not parallel to each other. Insome embodiments, the non-parallel laser emitter boards are adjacent toeach other. Therefore, it is contemplated that at least one of theplurality of laser emitter boards is not parallel to another laseremitter board adjacent to it.

In other embodiments, when two adjacent laser emitter boards are notparallel to each other, the other laser emitter boards may or may not beparallel between each other. In an example of six laser emitter boards,two of the laser emitter boards in the middle may form an acute angle tofocus the emitted laser beams while the other four on the outerperipheral may be parallel to each other. In another example of fourlaser emitter boards, each pair of adjacent laser emitter boards mayform an acute angle and none of the plurality of laser emitter boards isparallel to the laser emitter board adjacent to it.

FIG. 4B illustrates a schematic diagram of an exemplary arrangement oflaser emitter boards 111-115 of multi-beam LiDAR system 300. Each pairof adjacent laser emitter boards have an angle (α1, α2, α3, and α4).None of the angles is 0 degree. Thus, none of the plurality of laseremitter boards 111-115 is parallel to the laser emitter board adjacentto it. This non-parallel arrangement of laser emitter boards makes thelight-emitting surface more compact, thus reducing the volume ofsubsequent optical components, which in turn shrink the size of thetransmitter. Thus, the overall size of multi-beam LiDAR system 300 mayalso be reduced, as well as the manufacturing cost of multi-beam LiDARsystem 300.

Consistent with the embodiments of the present disclosure, the anglebetween two adjacent laser emitter boards may be fixed during themanufacturing stage or preset before each use. In embodiments where theangle is preset before each use, an angle adjusting mechanism (notshown) may be provided. The angle adjusting mechanism may change theorientation of one or both of the adjacent laser emitter boards in orderto obtain the desired angle for a particular application using themulti-beam LiDAR. The angle may be predetermined to be any value between0 and 180 degrees, for example, 1 degree, 2 degrees, 5 degrees, 10degrees, 15 degrees, etc. When N laser emitter boards are provided,there are N−1 angles between adjacent laser emitter boards (N>2). WhenN>3, there are two or more angles. In some embodiments, these angles maybe the same. In other embodiments, at least two of them are different.Where the two or more predetermined angles are different, the anglebetween two laser emitter boards that are closer to the center of thelaser emitter array (e.g., α2 or α3 in FIG. 4B) is smaller than theangle between two laser emitter boards that are farther away from thecenter of the laser emitter array (e.g., α1 or α4 in FIG. 4B). As aresult, the emitted beams may have a higher concentration at or near thecenter portion of the emitted laser beams, thus increasing the detectionaccuracy and resolution around that portion.

In some embodiments, photodetector array 120 may include two or morephotodetector columns. In the example illustrated in FIG. 3, fivephotodetector columns 121, 122, 123, 124, and 125 (hereinafter“photodetector columns 121-125”) are perpendicular a horizontal plane(e.g., x-z plane), and each photodetector column may extend along avertical direction (e.g., along y-axis, as shown in FIG. 4C),perpendicular to the horizontal plane. Each photodetector column mayinclude a plurality of photodetectors aligned in a vertical direction.

FIG. 4C illustrates a schematic diagram of an exemplary photodetectorarray of multi-beam LiDAR system 300, according to embodiments of thedisclosure. In some embodiments, one of photodetector columns 121-125may correspond to one of laser emitter boards 111-115 disposed inemitter array 110. In some embodiments, one photodetector on aphotodetector column may correspond to one laser emitter on a laseremitter board that corresponds to that photodetector column. Forexample, photodetectors in photodetector column 121 may receive thereturn beams that are reflected by an object from the laser beamsemitted by laser emitters on laser emitter board 111, photodetectors inphotodetector column 122 may receive the return beams that are reflectedby an object from the laser beams emitted by laser emitter board 112,and so on. In some embodiments, photodetectors in photodetector array120 of multi-beam LiDAR system 300 may also be staggered along thevertical direction (e.g., along y-axis), as shown in FIG. 4C. Therefore,photodetector array 120 may be able to receive a broader range of returnbeams in spite of the higher density of the laser beams, which areemitted by laser emitter array 110 having corresponding laser emittersstaggered along the same vertical direction.

In some embodiments, photodetector array 120 may be an individualphotodetector area array. In other embodiments, photodetector array 120may be an integrated photodetector array that consists of multipleindividual photodetector arrays, each of which has the similarconfiguration and design as the exemplary photodetector array discussedabove.

It is contemplated that the number of laser emitter boards included inemitter array 110 and the number of photodetector columns included inphotodetector array 120 are just for illustrative purpose and should notbe limited to five. For example, laser emitter array 110 may include 2,3, 4, 6, 7, 8, 9, 10, or more laser emitter boards, and photodetectorarray 120 may include 2, 3, 4, 6, 7, 8, 9, 10, or more photodetectorcolumns. In some embodiments, one photodetector column may correspond toone laser emitter board. In other embodiments, each photodetector columnmay correspond to one and only one laser emitter board, and thereforethe number of laser emitter boards is equal to that of photodetectorcolumns. Such a one-to-one design of laser emitter board andphotodetector column is relatively easy to be implemented and assembledthanks to its simplified configuration. In yet other embodiments, two ormore photodetector columns may correspond to one laser emitter board,which may increase the detection precision of the return beams.

Similarly, the number of laser emitters in each of the laser emitterboards and the number of photodetectors in each of the photodetectorcolumns are not limited to 4 or 5, as illustrated in FIGS. 4A and 4C. Itis understood that the number of emitters in each of the laser emitterboards and the number of photodetectors in each of the photodetectorcolumns may vary according to different performance requirements ofmulti-beam LiDAR system 300.

In some embodiments, multi-beam LiDAR system 300 may also include atransmitter optical unit 130 and a receiver optical unit 140.Transmitter optical unit 130 may be configured to collimate the laserbeams emitted from laser emitter array 110. For example, laser beamsemitted by laser emitter array 110 may be focused by transmitter opticalunit 130, and thus may reduce the spread and dispersion of the emittedlaser beams as the beams propagate. In some embodiments, to bettercollimate the emitted laser beams, a focal plane of transmitter opticalunit 130 may coincide with a light-emitting surface of laser emitterarray 110. The light-emitting surface of laser emitter array 110 may bea surface perpendicular to the laser beams emitted by laser emitterarray 110.

In some embodiments, receiver optical unit 140 may be configured tocollect laser beams reflected by the object and focus the light beforeit is received by photodetector array 120. The larger aperture receiveroptical unit 140 has, the greater number of return beams it may collect.As a result, more return beams may be focused by receiver optical unit140 and received by the photodetectors of photodetector array 120. Insome embodiments, to better focus the return beams, a focal plane ofreceiver optical unit 140 may coincide with a light-receiving surface ofphotodetector array 120. The light-receiving surface of photodetectorarray 120 may be a surface perpendicular to the reflect laser beamsreceived by the photodetectors of photodetector array 120. In someembodiments, an optical axis of transmitter optical unit 130 is parallelto an optical axis of receiver optical unit 140.

Consistent with some embodiments of the present disclosure, transmitteroptical unit 130 and receiver optical unit 140 may have the same size.For example, the area of the light-emitting surface may be the same asthe area of the light-receiving surface. In some other embodiments,transmitter optical unit 130 and receiver optical unit 140 may havedifferent sizes. Preferably, receiver optical unit 140 may have a largersize than transmitter optical unit 130. For example, the area of thelight-receiving surface may be larger than the area of thelight-emitting surface. This configuration of size difference betweentwo optical units may allow photodetector array 120 to capture moreinformation of the surrounding environment, as the return beams areusually more scattered after reflection by the object in the environmentthan the emitted laser beams.

In some embodiments, multi-beam LiDAR device 300 may include areflection mirror 150 disposed between receiver optical unit 140 andphotodetector array 120, as illustrated in FIG. 3. In some embodiments,reflection mirror 150 may be configured to redirect the laser beamsfocused by receiver optical unit 140 for reception by photodetectorarray 120. For example, when laser beams are emitted by laser emitterarray 110 and reflected by an object, receiver optical unit 140 mayreceive the return beams through its apertures. Reflection mirror 150may redirect return beams focused by receiver optical unit 140 to one ofthe photodetector columns that corresponds to the laser emitter boardthat emits the laser beams. For example, laser beams emitted by laseremitter board 111 may be reflected by an object and the resulted returnbeams may be received by receiver optical unit 140. Reflection mirror150 may redirect the return beams focused by receiver optical unit 140to photodctector column 121 of photodetector array 120.

In some embodiments, a central line of laser emitter array 110 may beperpendicular to a central line of photodetector array 120. Both centrallines are virtual lines that pass through laser emitter array 110 andphotodetector array 120, respectively. In situations where laser emitterarray 110 includes an odd number of laser emitter boards (such as 3, 5,7 or 9), the central line of laser emitter array 110 may coincide withthe line that passes through the center of the laser emitter boardlocated in the middle of laser emitter array 110. In situations wherelaser emitter array 110 includes an even number of laser emitter boards(such as 2, 4, 6, 8 or 10), the central line of laser emitter array 110may coincide with the line that lies between, and equally from, twocenter laser emitter boards located in the middle of laser emitter array110. For example, the central line of laser emitter array 110 havingfive laser emitter boards may coincide with the line that passes throughthe center of the third laser emitter board counted from the left (orright) of laser emitter array 110. In some embodiments, a central lineof photodetector array 120 may be a virtual line 190 that isperpendicular to a surface of a circuit on which photodetector array 120are arranged.

In some embodiments, multi-beam LiDAR system 300 may include astationary part 160, a rotating part 170, and a rotating apparatus (notshown in FIG. 3). Stationary part 160 may be connected to rotating part170 through the rotating apparatus. In some embodiments, the rotatingapparatus may use a communication module to communicate with rotatingpart 170. The communication module may have two differentimplementations. One is to use a wired connection, such as slip rings.The other is to use a wireless connection, such as using electrical ormagnetic signals to establish connections through electromagneticcoupling, to connect rotating apparatus with rotating part 170. Therotating apparatus may thus drive the rotation of rotating part 170.

In some embodiments, rotating part 170 rotates about an axisperpendicular to the horizontal plane (e.g., x-z plane). In someembodiments, laser emitter array 110, photodetector array 120,transmitter optical unit 130, receiver optical unit 140, and reflectionmirror 150 may all be disposed in rotating part 170. Thus, when rotatingpart 170 rotates, these components rotate together, which may allowmulti-beam LiDAR system 300 to perform a 360-degree detection of thesurrounding environment.

As its name suggests, stationary part 160 does not rotate together withrotating party 170. In some embodiments, stationary part 160 may includea base and a rotating shaft (not shown in FIG. 3).

FIG. 5 illustrates a top view of another exemplary multi-beam LiDARsystem 500, according to embodiments of the disclosure. In theseembodiments, multi-beam LiDAR system 500 may include a laser emitterarray 510, a photodetector array 520, a transmitter optical unit 530,and a receiver optical unit 540. Laser emitter array 510, photodetectorarray 520, transmitter optical unit 530, and receiver optical unit 540may have the same or similar function and configuration as laser emitterarray 110, photodetector array 120, transmitter optical unit 130, andreceiver optical unit 140, respectively, which are described in detailin conjunction with FIG. 3.

Consistent with the embodiments of the present disclosure, multi-beamLiDAR system 500 may also include a stationary part 560 and a rotatingpart 570, which have the same or similar function and configuration asstationary part 160 and rotating part 170, respectively, which are alsodescribed in detail in conjunction with FIG. 3. Likewise, similar to theembodiments of multi-beam LiDAR system 300, laser emitter array 510,photodetector array 520, transmitter optical unit 530, and receiveroptical unit 540 may all be disposed in rotating part 570. Thus, whenrotating part 570 rotates, these components rotate together, which mayallow multi-beam LiDAR system 500 to perform a 360-degree detection ofthe surrounding environment. Therefore, the same or similar function andconfiguration of these components will not be repeated here.

Different from multi-beam LiDAR system 300 illustrated in FIG. 3, thecentral line of laser emitter array 510 of multi-beam LiDAR system 500is parallel to the central line of photodetector array 520. In theseembodiments, multi-beam LiDAR system 500 does not need a reflectionmirror to redirect the return beams focused by receiver optical unit540. Return beams may directly project on the photodetectors ofphotodetector array 520 after passing through receiver optical unit 540.While achieving the same purpose of improving resolution of themulti-beam LiDAR as the embodiments above, this mirror-lessconfiguration may have the benefit of reduced size and complexity of themulti-beam LiDAR, thus making it easy to install and maintain. It mayalso reduce the cost of producing the multi-beam LiDAR because of thelack of the additional component (i.e. reflection mirror).

FIG. 6 illustrates a top view of another exemplary multi-beam LiDAR,according to embodiments of the disclosure. In this exemplary multi-beamLiDAR system 600, the plurality of laser emitter boards of its laseremitter array may be parallel among each other. As illustrated in FIG.6, multi-beam LiDAR system 600 may include a laser emitter array 610, aphotodetector array 620, a transmitter optical unit 630, and a receiveroptical unit 640. Laser emitter array 610, photodetector array 620,transmitter optical unit 630, and receiver optical unit 640 may have thesame or similar function and configuration as laser emitter array 510,photodetector array 520, transmitter optical unit 530, and receiveroptical unit 540, respectively, which are described in detail inconjunction with FIG. 5. Multi-beam LiDAR system 600 may also include astationary part 660 and a rotating part 670, which have the same orsimilar function and configuration as stationary part 560 and rotatingpart 570, respectively, which are also described in detail inconjunction with FIG. 5. Likewise, similar to the embodiments ofmulti-beam LiDAR system 500, laser emitter array 610, photodetectorarray 620, transmitter optical unit 630, and receiver optical unit 640may all be disposed in rotating part 670. Thus, when rotating part 670rotates, these components rotate together, which may allow multi-beamLiDAR system 600 to perform a 360-degree detection of the surroundingenvironment. Therefore, the same or similar function and configurationof these components will not be repeated here.

Different from multi-beam LiDAR systems 300 or 500, the plurality oflaser emitter boards of laser emitter array 610 in multi-beam LiDARsystem 600 may be parallel among each other. This may allow laseremitter array 610 to emit telecentric laser beams, since the laser beamsemitted from the parallel laser emitter boards are parallel to eachother. This may have the benefit of reducing the size of multi-beamLiDAR system 600, particularly of the portion that houses laser emitterarray 610, as parallel laser emitter boards do not have a fan-shapedrear end that occupies additional space. Parallel laser emitter boardsare also easy to be installed and adjusted. Furthermore, the cloud dataobtained from laser beams emitted by parallel laser emitter boards arealso more uniform than non-parallel laser emitter boards.

In some embodiments, the multi-beam LiDAR in the embodiments disclosedherein may further include a processor (not shown) configured to controla time point and a light path of each of the laser emitter within thelaser emitter array. The processor may also control the rotating speedand the rotation range of the rotating part to create a field of viewcovering surrounding environment of the multi-beam LiDAR system. Theprocessor may include a microprocessor, a digital signal processor(DSP), a microcontroller, a field programmable gate array (FPGA), and/orother suitable devices or chips capable of achieving the same or similarresult.

FIGS. 7-9 illustrates an internal configuration of an exemplarymulti-beam LiDAR system, according to embodiments of the disclosure. Insome embodiments, the multi-beam LiDAR system may include a transmitter1, a receiver 2, a transmitter optical unit 3, and a receiver opticalunit 4. Transmitter 1 may be configured to emit multiple laser beams todetect objects within surrounding environment. Receiver 2 may beconfigured to receive laser beams reflected by the object and convertthe light signals to electrical signals. Transmitter 1 may include thesame laser emitter array as disclosed in conjunction with any one ofFIG. 3, 5, or 6. Receiver 2 may include the same photodetector array asdisclosed in conjunction with any one of FIG. 3, 5, or 6. Transmitteroptical unit 3 may be configured to collimate the emitted laser beamsfor better scanning performance. Receiver optical unit 4 may beconfigured to receive the return beams and focus the received laserbeams before they reach receiver 2. In some embodiments, a center lineof transmitter 1 may be collinear to a center line of transmitteroptical unit 3.

In some embodiments, transmitter 1 may be disposed on the rear part ofone side of the multi-beam LiDAR system, facing towards the front partof the multi-beam LiDAR and aligning with transmitter optical unit 3.Receiver 2 may be disposed on a lateral part of the other side of themulti-beam LiDAR system, facing towards a center of the multi-beam LiDARand aligning with the receiver optical unit. Consistent with theembodiments disclosed above and as illustrated in FIGS. 7 and 8,transmitter 1, receiver 2, transmitter optical unit 3, and receiveroptical unit 4 may all be disposed in a rotating system 5. In someembodiments, rotating system 5 rotates about a rotating shaft 81.Rotating shaft 81 may be fixed to a base 8 of the multi-beam LiDARsystem. In some preferred embodiments, rotating shaft 81 may be fixed tothe center of base 8.

In some embodiments, the multi-beam LiDAR system may further include ashell 9. Shell 9 may include a protector 91 and a cover 92. In someembodiments, rotating system 5 is disposed in a cavity encompassed byshell 9 and base 8. A circuit board 84 may be fixed to base 8. Rotatingshaft 81 may include a bearing 82 configured to support rotating system5, and a motor 83 configured to rotate rotating system 5. Motor 83 mayinclude a rotor and a stator. The stator may be fixed onto rotatingshaft 81 and the rotor may be fixed to rotating system 5.

A main circuit board 71 may be disposed on the top of rotating system 5.Main circuit board 71 may be fixed to rotating system 5 via a top plate72. Main circuit board 71 may be configured to transmit, generate, orstore control signals and/or received signals. It may also be configuredto process the received signals, such as converting the light signalsinto electrical signals, amplifying the electrical signals, andconverting the electrical signals into point cloud data. In someembodiments, main circuit board 71 may be configured to only temporarilystore the data, and the data may be transmitted to a server or anotherprocessor for further processing.

As illustrated in FIG. 9, in some embodiments, transmitter 1 may includeone or more laser emitter boards 11. Laser emitter boards 11 may befixed by a support frame 14 and a light adjusting frame 13. Consistentwith embodiments disclosed herein, each of the plurality of laseremitter boards 11 may include multiple emitters. Laser emitter boards 11may be fixed to rotating system 5 through light adjusting frame 13. Thetop part of laser emitter boards 11 may be fixed by support frame 14. Insome embodiments, two or more laser emitter boards 11 may be parallel toeach other. In other embodiments, a first laser emitter board is at anangle α (such as an angle α less than 90 degrees) with a second laseremitter board adjacent to the first laser emitter board.

Consistent with the embodiments of the present disclosure, transmitter 1may further include a grating 12. Grating 12 may be configured to reduceor eliminate the interference between the emitted laser beams, thusincreasing the precision and accuracy of detection by the multi-beamLiDAR system.

In some embodiments, receiver 2 may include one or more receiving boards21 and a filter 22. Receiving boards 21 may be fixed by a receivingboard seat 23. Filter 22 may be disposed in front of receiving boards 21and fixed to receiving board seat 23 by a filter frame 24.

In some embodiments, receiver optical unit 4 includes a receiving lensset 41 and an optional reflection mirror 42. Reflection mirror may befixed by a mirror support frame 49. Reflection mirror 42 may beconfigured to redirect the laser beams received by receiving lens set 41to the photodetector array of receiver 2. When reflection mirror 42 ispresent, the photodetector array may be disposed on a lateral part ofthe receiver side of the multi-beam LiDAR system. When reflection mirror42 is not equipped, the photodetector array may be disposed on a rearpart of the receiver side of the multi-beam LiDAR system. In someembodiments, receiving lens set 41 may include a plurality of lenseshoused in a receiving lens barrel 47. Transmitter optical unit 3 mayinclude a transmitting lens set 31, which may include a plurality oflenses housed in a transmitting lens barrel 37. Receiving lens barrel 47and transmitting lens barrel 37 may both be fixed to a lens barrel base45.

In some embodiments, the multi-beam LiDAR system may further include anadapter system 6. Adapter system 6 may include an adapter board 61, anadapter seat 62, and a block 63. Adapter board 61 may connect maincircuit board 71 with laser emitter boards 11 and receiving boards 21for signal transmission. Adapter board 61 may be fixed to rotatingsystem 5 via adapter seat 62. Block 63 may be mounted on top of adapterboard 61 and installed to adapter seat 62 via a buckle in order tofirmly press the data cables on adapter board 61 and prevent them fromgetting loose while being rotated.

In some embodiments, the multi-beam LiDAR system may further include abalance system 7. Balance system 7 may be a weight configured to adjustthe center of gravity of rotating system 5. This may cause the center ofgravity of rotating system 5 to fall on rotating shaft 81 so that therotation is ensured to be smooth.

FIG. 10 illustrates a flow chart of an exemplary method for detection bya multi-beam LiDAR system, according to embodiments of the disclosure.In some embodiments, method 1000 may be implemented by a multi-beamLiDAR system disclosed herein, which includes a processor that performsvarious operations. It is to be appreciated that some of the steps maybe optional to perform the disclosure provided herein, and that somesteps may be inserted in the flowchart of method 1000 that areconsistent with other embodiments according to the current disclosure.Further, some of the steps may be performed simultaneously, or in anorder different from that shown in FIG. 10.

At step S1002, laser beams are emitted by a transmitter. In someembodiments, the transmitter may include a laser emitter array that hasthe same or similar function and configuration as any laser emitterarray disclosed herein. In some embodiments, one of the plurality oflaser emitter boards may be at an angle with another laser emitterboard. When the angle is not 0 or 180 degrees, the two laser emitterboards are not parallel to each other. In some other embodiments, atleast one of the plurality of laser emitter boards may be parallel toanother laser emitter board adjacent to the first laser emitter board.

At step S1004, return beams that are reflected by objects from laserbeams emitted from the laser emitter boards are received by receiver 2.In some embodiments, receiver 2 may include a photodetector array thathas the same or similar function and configuration as any photodetectorarray disclosed herein. In some embodiments, one photodetector column ofthe photodetector array of receiver 2 may correspond to one laseremitter board of the laser emitter array of transmitter 1, and eachphotodetector within the photodetector column corresponds to a laseremitter disposed on the corresponding laser emitter board.

At step S1006, light signals embodied in the return beams may beconverted into electrical signals (e.g., current signals or voltagesignals) by a processor. The converted electrical signals may beamplified by an amplifier (e.g., a transimpedance amplifier) and mayfurther be processed to generate data, such as point clouds.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed systems andrelated methods. Other embodiments will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosed systems and related methods.

It is intended that the specification and examples be considered asexemplary only, with a true scope being indicated by the followingclaims and their equivalents.

What is claimed is:
 1. A multi-beam LiDAR system, comprising: atransmitter having an array of laser emitters, each laser emitter beingconfigured to emit at least one laser beam; and a receiver having anarray of photodetectors, each photodetector being configured to receiveat least one return beam that is reflected by an object from one laserbeam emitted by the array of laser emitters, wherein the laser emitterarray comprises a plurality of laser emitter boards perpendicular to ahorizontal plane, each laser emitter board having a plurality of laseremitters, wherein the plurality of laser emitters in the laser emitterarray are staggered along a vertical direction, and wherein thephotodetector array comprises a plurality of columns of photodetectors,one of the plurality of laser emitter boards corresponding to one of theplurality of columns of photodetectors, wherein at least one of theplurality of laser emitter boards is not parallel to another laseremitter board adjacent to the one laser emitter board, wherein eachadjacent pair of laser emitter boards of the plurality of laser emitterboards comprises two laser emitter boards that are not parallel to oneanother, wherein any two adjacent laser emitter boards of the pluralityof laser emitter boards are at a predetermined angle, wherein, there aretwo or more predetermined angles between adjacent pairs of the pluralityof laser emitter boards, at least two of the two or more predeterminedangles are different from each other, and wherein the predeterminedangle between two laser emitter boards that are closer to the center ofthe laser emitter array is smaller than the predetermined angle betweentwo laser emitter boards that are farther away from the center of thelaser emitter array.
 2. The multi-beam LiDAR system of claim 1, whereineach column of photodetectors receive the return beams that arereflected from the laser beams emitted from a laser emitter boardcorresponding to the column.
 3. The multi-beam LiDAR system of claim 1,further comprising: a transmitter optical unit configured to collimatethe laser beams emitted from the laser emitter array, wherein a focalplane of the transmitter optical unit coincides with a light-emittingsurface of the laser emitter array; and a receiver optical unitconfigured to focus the return beams reflected by the object, wherein afocal plane of the receiver optical unit coincides with alight-receiving surface of the photodetector array, wherein an opticalaxis of the transmitter optical unit is parallel to an optical axis ofthe receiver optical unit.
 4. The multi-beam LiDAR system of claim 1,wherein a central line of the laser emitter array is parallel to acentral line of the photodetector array.
 5. The multi-beam LiDAR systemof claim 3, further comprising a reflection mirror disposed between thereceiver optical unit and the photodetector array, wherein thereflection mirror is configured to redirect the return beams focused bythe receiver optical unit for reception by the photodetector array. 6.The multi-beam LiDAR system of claim 5, wherein a central line of thelaser emitter array is perpendicular to a central line of thephotodetector array.
 7. The multi-beam LiDAR system of claim 5, whereinthe laser emitter array is disposed on a rear part of one side of themulti-beam LiDAR system, facing towards the front part of the multi-beamLiDAR system and aligning with the transmitter optical unit, and whereinthe photodetector array is disposed on a lateral part of the other sideof the multi-beam LiDAR system, facing towards a center of themulti-beam LiDAR system and aligning with the receiver optical unit. 8.The multi-beam LiDAR system of claim 1, wherein the transmitter furthercomprises a grating disposed in front of the plurality of laser emitterboards, and wherein the plurality of laser emitter boards are fixed tothe multi-beam LiDAR system by a light adjusting frame and a supportframe.
 9. The multi-beam LiDAR system of claim 1, wherein, if there aretwo or more predetermined angles, the two or more predetermined anglesare the same.
 10. The multi-beam LiDAR system of claim 1, wherein thereceiver further comprises a receiving board and a filter, wherein thereceiving board is fixed to the multi-beam LiDAR system by a receivingboard seat, and wherein the filter is disposed in front of the receivingboard and is fixed to the receiving board seat by a filter frame. 11.The multi-beam LiDAR system of claim 3, wherein the receiver opticalunit further comprises a receiving lens set, wherein the receiving lensset comprises a plurality of lenses housed in a receiving lens barrel.12. The multi-beam LiDAR system of claim 3, wherein the transmitteroptical unit comprises a plurality of lenses housed in a transmittinglens barrel.
 13. The multi-beam LiDAR system of claim 3, wherein thesize of the receiver optical unit may be larger than the size of thetransmitter optical unit.
 14. The multi-beam LiDAR system of claim 1,further comprising: a rotating reflection mirror configured to changethe direction of laser beams emitted from the laser emitter array,wherein the rotating reflection mirror is disposed outside thetransmitter and the receiver.
 15. A multi-beam LiDAR system, comprising:a transmitter having an array of laser emitters, each laser emitterbeing configured to emit a laser beam; a receiver having an array ofphotodetectors, each photodetector being configured to receive at leastone return beam that is reflected by an object from one of the laserbeams; and a reflection mirror disposed between a receiver optical unitof the receiver and the photodetector array, wherein the laser emitterarray comprises a plurality of laser emitter boards perpendicular to ahorizontal plane, each laser emitter board having a plurality of laseremitters, wherein the plurality of laser emitters in the laser emitterarray are staggered along a vertical direction, wherein thephotodetector array comprises a plurality of columns of photodetectors,one of the plurality of laser emitter boards corresponding to one of theplurality of columns of photodetectors, wherein the reflection mirror isconfigured to redirect the return beams focused by the receiver opticalunit for reception by the photodetector array, wherein the laser emitterarray is disposed on a rear part of one side of the multi-beam LiDARsystem, facing towards the front part of the multi-beam LiDAR system andaligning with the transmitter optical unit, and wherein thephotodetector array is disposed on a lateral part of the other side ofthe multi-beam LiDAR system, facing towards a center of the multi-beamLiDAR system and aligning with the receiver optical unit.
 16. Themulti-beam LiDAR system of claim 15, wherein each column ofphotodetectors receive the return beams that are reflected from thelaser beams emitted from a laser emitter board corresponding to thecolumn.
 17. The multi-beam LiDAR system of claim 15, wherein at leastone of the plurality of laser emitter boards is not parallel to anotherlaser emitter board adjacent to the one laser emitter board.
 18. Themulti-beam LiDAR system of claim 17, wherein none of the plurality oflaser emitter boards is parallel to the laser emitter board adjacent toit.
 19. The multi-beam LiDAR system of claim 15, wherein the pluralityof laser emitter boards are parallel among each other.
 20. Themulti-beam LiDAR system of claim 15, wherein the transmitter furthercomprises a grating disposed in front of the plurality of laser emitterboards, and wherein the plurality of laser emitter boards are fixed tothe multi-beam LiDAR system by a light adjusting frame and a supportframe.